1. Field of the Invention
The present invention is concerned with a pumping arrangement for optically pumping solid state lasers by using at least one pumping light source having a point form or shape. The arrangement is particularly advantageous in all cases in which the diameter of the laser rod is small in comparison to the absorption length for the pumping radiation in the laser material.
2. Prior Art
With the aid of spectrally matched light sources such as light emitting diodes or semiconductor diode lasers, solid state lasers and particularly YAG:Nd.sup.3.sup.+ lasers may be pumped. Utilizing such a pumping arrangement, continuous operation at 77 K as well as at room temperature was desired.
In case of the known arrangements, laser crystals or rods are either pumped from the side or pumped from one end. When pumping from the side, only a small portion of the energy supplied can be absorbed because of the small material thickness. Due to the focusing effect caused by round laser rods, the center of the rod is usually more strongly pumped than the edge zones. This occurs even if a large number of pumping diodes is utilized.
When pumping the laser rod by applying the pumping light to one end, nearly the entire light energy is absorbed in the laser rod or crystal and a more homogeneous illumination is obtained. However, the resonator reflector arranged at the end of the laser rod must have a good transmission for the pumping energy. In the case of known arrangements for pumping the end of a laser rod, it has not yet been possible to couple more than one pumping diode and, therefore, the light energy being applied to the rod remains substantially limited.